1. Field of the Invention
The present invention relates to a method of completing a well and also to one or more devices for use downhole and more particularly but not exclusively relates to a substantially interventionless method for completing an oil and gas wellbore with a production tubing string and a completion without requiring intervention equipment such as slick line systems to set downhole tools to install the completion.
2. History of the Related Art
Conventionally, as is well known in the art, oil and gas wellbores are drilled in the land surface or subsea surface with a drill bit on the end of a drillstring. The drilled borehole is then lined with a casing string (and more often than not a liner string which hangs off the bottom of the casing string). The casing and liner string if present are cemented into the wellbore and act to stabilise the wellbore and prevent it from collapsing in on itself.
Thereafter, a further string of tubulars is inserted into the cased wellbore, the further string of tubulars being known as the production tubing string having a completion on its lower end. The completion/production string is required for a number of reasons including protecting the casing string from corrosion/abrasion caused by the produced fluids and also for safety and is used to carry the produced hydrocarbons from the production zone up to the surface of the wellbore.
Conventionally, the completion/production string is run into the cased borehole where the completion/production string includes various completion tools such as:—                a barrier which may be in the form of a flapper valve or the like;        a packer which can be used to seal the annulus at its location between the outer surface of the completion string and the inner surface of the casing in order to ensure that the produced fluids all flow into the production tubing; and        a circulation sleeve valve used to selectively circulate fluid from out of the throughbore of the production tubing and into the annulus between the production string and the inner surface of the casing string in order to for example flush kill fluids up the annulus and out of the wellbore.        
It is known to selectively activate the various completion tools downhole in order to set the completion in the cased wellbore by one of two main methods. Firstly, the operator of the wellbore can use intervention equipment such as tools run into the production tubing on slickline that can be used to set e.g. the barrier, the packer or the circulation sleeve valve. However, such intervention equipment is expensive as an intervention rig is required and there are also a limited number of intervention rigs and also personnel to operate the rigs and so significant delays and costs can be experienced in setting a completion.
Alternatively, the completion/production string can be run into the cased wellbore with for example electrical cables that run from the various tools up the outside of the production string to the surface such that power and control signals can be run down the cables. However, the cables are complicated to fit to the outside of the production string because they must be securely strapped to the outside of the string and also must pass over the joints between each of the individual production tubulars by means of cable protectors which are expensive and timely to fit. Furthermore, it is not unknown for the cables to be damaged as they are run into the wellbore which means that the production tubing must be pulled out of the cased wellbore and further delays and expense are experienced.
It would therefore be desirable to be able to obviate the requirement for either cables run from the downhole completion up to the surface and also the need for intervention to be able to set the various completion tools.